mssql_upsert.sql

MERGE INTO Target_Table AS t
  USING 
    (SELECT Field1=?, Field2=?, Field3=?, Field4=?) AS s
  ON t.Field1 = s.Field1
  WHEN MATCHED THEN
    UPDATE SET 
      Field1=s.Field1, 
      Field2=s.Field2, 
      Field3=s.Field3, 
      Field4=s.Field4
  WHEN NOT MATCHED THEN
    INSERT (Field1, Field2, Field3, Field4) 
    VALUES (s.Field1, s.Field2, s.Field3, s.Field4);